柴油机富氧燃烧粒径分布和颗粒物排放特性研究

Study on Particle Size Distribution and Particulate Matter Emission Characteristics in Oxygen- enriched Combustion of Diesel Engine

为了研究柴油发动机颗粒物排放特性,在柴油机上利用不同进气氧体积分数,实现发动机富氧燃烧。试验中进气氧体积分数分别为21%,23%,25%,27%和29%,采用DMS500型快速颗粒光谱仪测试分析了发动机在不同负荷时的颗粒物数量浓度、质量浓度及粒径分布。研究结果表明:随进气氧体积分数的增加,颗粒物质量浓度降低;富氧燃烧的柴油发动机颗粒物的数量浓度在大、中负荷明显降低,小负荷呈升高趋势;富氧燃烧发动机的排放颗粒物呈核态和凝聚态的双峰分布特征,富氧燃烧核态数量浓度所占比例高于氧体积分数为21%的核态数量浓度,凝聚态的质量浓度所占比例低于氧体积分数为21%的质量浓度;富氧燃烧颗粒物的几何平均直径小于氧体积分数为21%颗粒物的几何平均直径。

To study the characteristics of particulate matter emission of diesel engine,oxygen-enriched combustion is realized in a diesel engine by controlling different intake oxygen volume fraction. 21%,23%,25%,27% and 29% intake oxygen volume fractions are used in the test,the particle number（ PN）concentration,particle mass（ PM） concentration,and particle size distribution are measured by DMS500 particulate spectrometer. The result shows that（ 1） PM concentration decreased with the increase of intake oxygen volume fraction;（ 2） the PN concentration decreased significantly under high and medium loads,while it increased under low loads;（ 3） bimodal distribution is observed corresponding to nucleation mode and accumulation mode of the particles,comparing with 21% intake oxygen volume fraction,oxygen-enriched combustion exhibited higher percentage of nucleation mode PN emissions and lower percentage of accumulation mode PM emission. Also,oxygen-enriched combustion exhibited smaller particulate mean diameter than that of 21% intake oxygen volume fraction.